Add DnsSvcbPacket
DnsSvcbPacket will be used to parse DNS packet of type SVCB.
Bug: 240259333
Test: will add some tests in a follow-up change
Change-Id: Icb13d50f2d95a898b3b7ea373db876f41690723a
diff --git a/staticlibs/Android.bp b/staticlibs/Android.bp
index 25a9291..6325b46 100644
--- a/staticlibs/Android.bp
+++ b/staticlibs/Android.bp
@@ -96,6 +96,7 @@
srcs: [
"framework/**/DnsPacket.java",
"framework/**/DnsPacketUtils.java",
+ "framework/**/DnsSvcbPacket.java",
"framework/**/DnsSvcbRecord.java",
"framework/**/HexDump.java",
"framework/**/NetworkStackConstants.java",
diff --git a/staticlibs/framework/com/android/net/module/util/DnsSvcbPacket.java b/staticlibs/framework/com/android/net/module/util/DnsSvcbPacket.java
new file mode 100644
index 0000000..c7ed3e6
--- /dev/null
+++ b/staticlibs/framework/com/android/net/module/util/DnsSvcbPacket.java
@@ -0,0 +1,182 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.net.module.util;
+
+import static android.net.DnsResolver.TYPE_A;
+import static android.net.DnsResolver.TYPE_AAAA;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.text.TextUtils;
+import android.util.Log;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.StringJoiner;
+
+/**
+ * A class for a DNS SVCB response packet.
+ *
+ * @hide
+ */
+public class DnsSvcbPacket extends DnsPacket {
+ public static final int TYPE_SVCB = 64;
+
+ private static final String TAG = DnsSvcbPacket.class.getSimpleName();
+
+ /**
+ * Creates a DnsSvcbPacket object from the given wire-format DNS packet.
+ */
+ private DnsSvcbPacket(@NonNull byte[] data) throws DnsPacket.ParseException {
+ // If data is null, ParseException will be thrown.
+ super(data);
+
+ final int questions = mHeader.getRecordCount(QDSECTION);
+ if (questions != 1) {
+ throw new DnsPacket.ParseException("Unexpected question count " + questions);
+ }
+ final int nsType = mRecords[QDSECTION].get(0).nsType;
+ if (nsType != TYPE_SVCB) {
+ throw new DnsPacket.ParseException("Unexpected query type " + nsType);
+ }
+ }
+
+ /**
+ * Returns true if the DnsSvcbPacket is a DNS response.
+ */
+ public boolean isResponse() {
+ return mHeader.isResponse();
+ }
+
+ /**
+ * Returns whether the given protocol alpn is supported.
+ */
+ public boolean isSupported(@NonNull String alpn) {
+ return findSvcbRecord(alpn) != null;
+ }
+
+ /**
+ * Returns the TargetName associated with the given protocol alpn.
+ * If the alpn is not supported, a null is returned.
+ */
+ @Nullable
+ public String getTargetName(@NonNull String alpn) {
+ final DnsSvcbRecord record = findSvcbRecord(alpn);
+ return (record != null) ? record.getTargetName() : null;
+ }
+
+ /**
+ * Returns the TargetName that associated with the given protocol alpn.
+ * If the alpn is not supported, -1 is returned.
+ */
+ public int getPort(@NonNull String alpn) {
+ final DnsSvcbRecord record = findSvcbRecord(alpn);
+ return (record != null) ? record.getPort() : -1;
+ }
+
+ /**
+ * Returns the IP addresses that support the given protocol alpn.
+ * If the alpn is not supported, an empty list is returned.
+ */
+ @NonNull
+ public List<InetAddress> getAddresses(@NonNull String alpn) {
+ final DnsSvcbRecord record = findSvcbRecord(alpn);
+ if (record == null) return Collections.EMPTY_LIST;
+
+ // As per draft-ietf-dnsop-svcb-https-10#section-7.4 and draft-ietf-add-ddr-10#section-4,
+ // if A/AAAA records are available in the Additional section, use the IP addresses in
+ // those records instead of the IP addresses in ipv4hint/ipv6hint.
+ final List<InetAddress> out = getAddressesFromAdditionalSection();
+ if (out.size() > 0) return out;
+
+ return record.getAddresses();
+ }
+
+ /**
+ * Returns the value of SVCB key dohpath that associated with the given protocol alpn.
+ * If the alpn is not supported, a null is returned.
+ */
+ @Nullable
+ public String getDohPath(@NonNull String alpn) {
+ final DnsSvcbRecord record = findSvcbRecord(alpn);
+ return (record != null) ? record.getDohPath() : null;
+ }
+
+ /**
+ * Returns the DnsSvcbRecord associated with the given protocol alpn.
+ * If the alpn is not supported, a null is returned.
+ */
+ @Nullable
+ private DnsSvcbRecord findSvcbRecord(@NonNull String alpn) {
+ for (final DnsRecord record : mRecords[ANSECTION]) {
+ if (record instanceof DnsSvcbRecord) {
+ final DnsSvcbRecord svcbRecord = (DnsSvcbRecord) record;
+ if (svcbRecord.getAlpns().contains(alpn)) {
+ return svcbRecord;
+ }
+ }
+ }
+ return null;
+ }
+
+ /**
+ * Returns the IP addresses in additional section.
+ */
+ @NonNull
+ private List<InetAddress> getAddressesFromAdditionalSection() {
+ final List<InetAddress> out = new ArrayList<InetAddress>();
+ if (mHeader.getRecordCount(ARSECTION) == 0) {
+ return out;
+ }
+ for (final DnsRecord record : mRecords[ARSECTION]) {
+ if (record.nsType != TYPE_A && record.nsType != TYPE_AAAA) {
+ Log.d(TAG, "Found type other than A/AAAA in Additional section: " + record.nsType);
+ continue;
+ }
+ try {
+ out.add(InetAddress.getByAddress(record.getRR()));
+ } catch (UnknownHostException e) {
+ Log.w(TAG, "Failed to parse address");
+ }
+ }
+ return out;
+ }
+
+ @Override
+ public String toString() {
+ final StringJoiner out = new StringJoiner(" ");
+ out.add("QUERY: [" + TextUtils.join(", ", mRecords[QDSECTION]) + "]");
+ out.add("ANSWER: [" + TextUtils.join(", ", mRecords[ANSECTION]) + "]");
+ out.add("AUTHORITY: [" + TextUtils.join(", ", mRecords[NSSECTION]) + "]");
+ out.add("ADDITIONAL: [" + TextUtils.join(", ", mRecords[ARSECTION]) + "]");
+ return out.toString();
+ }
+
+ /**
+ * Creates a DnsSvcbPacket object from the given wire-format DNS answer.
+ */
+ public static DnsSvcbPacket fromResponse(@NonNull byte[] data) throws DnsPacket.ParseException {
+ DnsSvcbPacket out = new DnsSvcbPacket(data);
+ if (!out.isResponse()) {
+ throw new DnsPacket.ParseException("Not an answer packet");
+ }
+ return out;
+ }
+}